Personal self-awareness, no side effects, can aid pregnancy achievement, in accord with Catholic teachings, nothing explicitly blocking the possibility of pregnancy can affect intercourse

Natural family planning (NFP) comprises the family planning methods approved by the Roman Catholic Church for both achieving and postponing or avoiding pregnancy. In accordance with the Church's teachings regarding sexual behavior in keeping with its philosophy of the dignity of the human person, NFP excludes the use of other methods of birth control, which it refers to as "artificial contraception."

Periodic abstinence is deemed moral by the Church for avoiding or postponing pregnancy for just reasons.[1] When used to avoid pregnancy, couples may engage in sexual intercourse during a woman's naturally occurring infertile times such as: during portions of her ovulatory cycle. Various methods may be used to identify whether a woman is likely to be fertile; this information may be used in attempts to either avoid or achieve pregnancy.

A study of 19,843 women in India (52% Hindu, 27% Muslim, and 21% Christian) using natural family planning to avoid pregnancy had an unexpected pregnancy rate of 0.2 pregnancy/100 women users yearly. A German study had an unexpected pregnancy rate of 0.8 pregnancy/100 women users yearly. [2]

Natural family planning has shown very weak and contradictory results in pre-selecting the gender of a child, with the exception of a Nigerian study at odds with all other findings. Because of these remarkable results, an independent study needs to be repeated in other populations. [3][4]

Possibly the earliest Christian writing about periodic abstinence was by Clement of Alexandria. He wrote, "Let the Educator (Christ) put us to shame with the word of Ezekiel: "Put away your fornications." [Eze. 43:9] Why, even unreasoning beasts know enough not to mate at certain times. To indulge in intercourse without intending children is to outrage nature, whom we should take as our instructor."[5][5]

In the year 388, St. Augustine wrote, "Is it not you who used to counsel us to observe as much as possible the time when a woman, after her purification, is most likely to conceive, and to abstain from cohabitation at that time...?"[6] The Manichaeans (the group the early church father St. Augustine wrote of and considered to be heretics) believed that it was immoral to create any children, thus (by their belief system), trapping souls in mortal bodies. Augustine condemned them for their use of periodic abstinence: "From this it follows that you consider marriage is not to procreate children, but to satiate lust."[6]

Saint Thomas Aquinas wrote in his Summa Contra Gentiles: "Hence it is clear that every emission of the semen is contrary to the good of man, which takes place in a way whereby generation is impossible; and if this is done on purpose, it must be a sin. I mean a way in which generation is impossible in itself as is the case in every emission of the semen without the natural union of male and female: wherefore such sins are called 'sins against nature.' But if it is by accident that generation cannot follow from the emission of the semen, the act is not against nature on that account, nor is it sinful; the case of the woman being barren would be a case in point."[7]

However, the Council of Trent issued the following anathema: "If any one saith, that the Church errs, in that she declares that, for many causes, a separation may take place between husband and wife, in regard of bed, or in regard of cohabitation, for a determinate or for an indeterminate period; let him be anathema." [2]

If the Manichaeans had an accurate idea of the fertile portion of the menstrual cycle, such knowledge died with them.[8] Documented attempts to prevent pregnancy by practicing periodic abstinence do not appear again until the mid-19th century, when various calendar-based methods were developed "by a few secular thinkers."[9] The Roman Catholic Church's first recorded official statement on periodic abstinence to avoid pregnancy is from 1853, where a ruling of the church's Sacred Penitentiary addressed the topic of periodic abstinence to avoid pregnancy. Distributed to confessors, the ruling stated that couples who had, on their own, begun the practice of periodic abstinence—especially if they had "legitimate reasons"—were not sinning by doing so.[10]

In 1880, the Sacred Penitentiary reaffirmed the 1853 ruling, and went slightly further. It suggested that, in cases where the couple was already practicing artificial birth control, and could not be dissuaded to cease attempting birth regulation, the confessor might morally teach them of periodic abstinence.[10]

In 1905, Theodoor Hendrik van de Velde, a Dutch gynecologist, showed that women only ovulate once per menstrual cycle.[11] In the 1920s, Kyusaku Ogino, a Japanese gynecologist, and Hermann Knaus, from Austria, working independently, each made the discovery that ovulation occurs about fourteen days before the next menstrual period.[12] Ogino used his discovery to develop a formula for use in aiding infertile women to time intercourse to achieve pregnancy.

In 1930, John Smulders, a Roman Catholic physician from the Netherlands, used Knaus and Ogino's discoveries to create a method for avoiding pregnancy. Smulders published his work with the Dutch Roman Catholic medical association, and this was the official rhythm method promoted over the next several decades.[12] While maintaining procreation as the primary function of intercourse, the December 1930 encyclical Casti connubii by Pope Pius XI gave the highest form of recognition to a secondary—unitive—purpose of sexual intercourse. This encyclical stated that there was no moral stain associated with having marital intercourse at times when "new life cannot be brought forth." Although this referred primarily to conditions such as current pregnancy and menopause, the Sacred Penitentiary in yet another ruling in 1932,[13] and the majority of Catholic theologians also interpreted it to allow moral use—for couples with "upright motives"—of the newly created rhythm method.[10][14]:231

In 1932, a Catholic physician published a book titled The Rhythm of Sterility and Fertility in Women describing the method,[9] and the 1930s also saw the first U.S. Rhythm Clinic (founded by John Rock) to teach the method to Catholic couples.[15] It was during this decade that Rev. Wilhelm Hillebrand, a Catholic priest in Germany, developed a system for avoiding pregnancy based on basal body temperature.[16]

A minority of Catholic theologians continued to doubt the morality of periodic abstinence.[10] Some historians consider two speeches delivered by Pope Pius XII in 1951[17] to be the first unequivocal acceptance of periodic abstinence by the Catholic Church.[9] The 1950s also saw another major advance in fertility awareness knowledge: Dr. John Billings discovered the relationship between cervical mucus and fertility while working for the Melbourne Catholic Family Welfare Bureau. Dr. Billings and several other physicians studied this sign for a number of years, and by the late 1960s had performed clinical trials and begun to set up teaching centers around the world.[18]

Humanae Vitae, published in 1968 by Pope Paul VI, addressed a pastoral directive to scientists: "It is supremely desirable... that medical science should by the study of natural rhythms succeed in determining a sufficiently secure basis for the chaste limitation of offspring." This is interpreted as favoring the then-new, more reliable symptoms-based fertility awareness methods over the rhythm method. Just a few years later, in 1971, the first organization to teach a symptothermal method (one that used both mucus and temperature observations) was started. Now called Couple to Couple League International, this organization was founded by John and Sheila Kippley, lay Catholics, along with Dr. Konald Prem.[16] During the following decade, other now-large Catholic organizations were formed: Family of the Americas(1977), [19] and the Creighton Model as part of the Pope Paul VI Institute (1985),[20] both mucus based systems of NFP.

Today, use of the term natural family planning to describe calendar-based methods is considered incorrect by the United States Conference of Catholic Bishops: it considers such methods "inaccurate".[21] Still, some organizations still consider calendar-based methods to be forms of NFP.[14]:154 For example, in 1999 the Institute for Reproductive Health at Georgetown University developed the Standard Days Method (SDM), which is more effective than the rhythm method.[22] SDM is promoted by Georgetown University as a form of natural family planning.[23]

It is estimated that 2%–3% of the world's reproductive age population relies on periodic abstinence to avoid pregnancy.[24] However, what portion of this population should be considered NFP users is unclear. Some Catholic sources consider couples that violate the religious restrictions associated with natural family planning to not be NFP users.[14]:13[25]

There is little data on the worldwide use of natural family planning. In Brazil, NFP is the third most popular family planning method.[26] The "safe period" method of fertility awareness is the most common family planning method used in India, although condoms are used by some.[27]

Use of NFP in developed countries is low, even among Catholics. While Catholics made up 24% of the U.S. population in 2002,[28] of reproductive age American women using birth control, only 1.5% were using periodic abstinence.[29] In Italy, where the vast majority of citizens claims to be Catholic, NFP methods are rarely taught.[30]

Use of NFP is not restricted to Catholic couples. In 2002, Sam and Bethany Torode, then a Protestant Christian couple, published a book advocating NFP use.[31] (Five years after writing the book, the Torodes retracted their advocacy of pure NFP and also supported barrier methods as moral; the couple converted from Protestantism to the Eastern Orthodox Church.)[32] In addition, many NFP clinics and teaching organizations are not specifically associated with the Catholic Church. It has been shared by members of The Church of Jesus Christ of Latter-day Saints (LDS Church)[33] and some members of the Muslim faith.[34]

Some proponents of NFP differentiate it from other forms of birth control by labeling them artificial birth control.[35][36] Other NFP literature holds that natural family planning is distinct from contraception.[37][38][39] Proponents justify this classification system by saying that NFP has unique characteristics not shared by any other method of birth regulation except for abstinence. Commonly cited traits are that NFP is "open to life,"[36][39] and that NFP alters neither the fertility of the woman nor the fecundity of a particular sex act.[37][38] That NFP can be used to both avoid or achieve pregnancy may also be cited as a distinguishing characteristic.[40] Additionally, NFP differs greatly from contraception because, according to action theory, NFP does not "break" the sexual act (separating the action from its purposes) in the way contraception does.

There are three main types of NFP: the symptoms-based methods, the calendar-based methods, and the breastfeeding or lactational amenorrhea method. Symptoms-based methods rely on biological signs of fertility, while calendar-based methods estimate the likelihood of fertility based on the length of past menstrual cycles.

Clinical studies by the Guttmacher Institute found that periodic abstinence resulted in a 25.3 percent failure under typical conditions, though it did not differentiate between symptom-based and calendar-based methods.[41]

Some methods of NFP track biological signs of fertility. When used outside of the Catholic concept of NFP, these methods are often referred to simply as fertility awareness-based methods rather than NFP.[42] The three primary signs of a woman's fertility are her basal body temperature, her cervical mucus, and her cervical position.[43] Computerized fertility monitors, such as Lady-Comp, may track basal body temperatures, hormonal levels in urine, changes in electrical resistance of a woman's saliva or a mixture of these symptoms.[44]

From these symptoms, a woman can learn to assess her fertility without use of a computerized device. Some systems use only cervical mucus to determine fertility. Two well-known mucus-only methods are the Billings ovulation method and the Creighton Model FertilityCare System. If two or more signs are tracked, the method is referred to as a symptothermal method. Two popular symptothermal systems are taught by the Couple to Couple League and the Fertility Awareness Method (FAM) taught by Toni Weschler.[45] A study completed in Germany in 2007 found that the symptothermal method has a method effectiveness of 99.6%.[46]

In Canada, the symptothermal method is taught by SERENA Canada which is an inter-denominational organization which has been developing the Symptothermal Method as a part of NFP since 1955. They are also not specifically affiliated with the Roman Catholic Church. It is also taught by Justisse Healthworks for Women, a pro-choice feminist organization that allows and supports women to combine other methods of birth control with their fertility awareness practice. A study by the World Health Organization involving 869 fertile women from Australia, India, Ireland, the Philippines, and El Salvador found that 93% could accurately interpret their body's signals regardless of education and culture.[47] In a 36-month study of 5,752 women, the method was 99.86% effective.[48]

Calendar-based methods determine fertility based on a record of the length of previous menstrual cycles. They include the Rhythm Method and the Standard Days Method. The Standard Days method was developed and proven by the researchers at the Institute for Reproductive Health of Georgetown University. CycleBeads, unaffiliated with religious teachings, is a visual tool based on the Standard Days method. According to the Institute of Reproductive Health, when used as birth control, CB has a 95% effectiveness rating. Computer programs are available to help track fertility on a calendar.[49]

The lactational amenorrhea method (LAM) is a method of avoiding pregnancy based on the natural postpartuminfertility that occurs when a woman is amenorrheic and fully breastfeeding. The rules of the method help a woman identify and possibly lengthen her infertile period.

Some Catholics have indicated significant disagreement with the Church's stance on contraception.[50] The Canadian Conference of Catholic Bishops issued what many interpreted as a dissenting document, the Winnipeg Statement. In it, the bishops recognized that many Catholics found it "either extremely difficult or even impossible to make their own all elements of this doctrine" (that of Humanae Vitae).[51] Additionally, they reasserted the Catholic principle of primacy of conscience,[51] a principle that they said should be properly interpreted, since they insisted that "a Catholic Christian is not free to form his conscience without consideration of the teaching of the magisterium, in the particular instance exercised by the Holy Father (i.e., the Pope) in an encyclical letter".[52]Catholics for a Free Choice claimed in 1998 that 96% of U.S. Catholic women had used contraceptives at some point in their lives and that 72% of Catholics believed that one could be a good Catholic without obeying the Church's teaching on birth control.[53] According to a nationwide poll of 2,242 U.S. adults surveyed online in September 2005 by Harris Interactive (they stated that the magnitude of errors cannot be estimated due to sampling errors, non-response, etc.), 90% of Catholics supported the use of birth control/contraceptives.[54] Use of natural family planning methods among United States Catholics purportedly is low, although the number cannot be known with certainty. In 2002, 24% of the U.S. population identified as Catholic.[28] But of sexually active Americans avoiding pregnancy, only 1.5% were using NFP.[29]

Much criticism of NFP stems from the Church's stance of NFP as the only allowable form of birth control. In 2009, Pope Benedict XVI asserted that handing out condoms is not the solution to combating AIDS and actually makes the problem worse.[55] Some senior Catholic authorities, such as Belgian Cardinal Emeritus Godfried Danneels, believe the Catholic Church should support condoms used to prevent serious diseases such as AIDS, because non-use is tantamount to murder.[56] In 2003, BBC's Panorama claimed that the Vatican is intentionally spreading lies that HIV can pass through the membrane of the condom.[57]

Family planning proponent Stephen D. Mumford has argued that the primary motivation behind the Church's continued opposition to contraceptive use is the Church's fear of losing papal authority if the pope were to contradict the dogma of papal infallibility.[58] Mumford gives as an example the citation made by August Bernhard Hasler of a comment by Pope John Paul II prior to his papacy:

If it should be declared that contraception is not evil in itself, then we should have to concede frankly that the Holy Spirit had been on the side of the Protestant churches in 1930 (when the encyclical Casti connubii was promulgated), in 1951 (Pius XII's address to the midwives), and in 1958 (the address delivered before the Society of Hematologists in the year the pope died). It should likewise have to be admitted that for a half century the Spirit failed to protect Pius XI, Pius XII, and a large part of the Catholic hierarchy from a very serious error. This would mean that the leaders of the Church, acting with extreme imprudence, had condemned thousands of innocent human acts, forbidding, under pain of eternal damnation, a practice which would now be sanctioned. The fact can neither be denied nor ignored that these same acts would now be declared licit on the grounds of principles cited by the Protestants, which popes and bishops have either condemned or at least not approved.[59]

However, none of the instances cited actually falls under the domain of papal infallibility, since the Pope is not considered infallible except in the rare, solemn occasions when he is speaking ex cathedra.[60] Even the encyclicals Casti connubii and Humanae vitae are considered by most, though not all, Catholic theologians to be non-infallible documents.[61]

Theological opposition has additionally come from Protestant Christianity. John Piper's Desiring God ministry states of NFP, "There is no reason to conclude that natural family planning is appropriate but that 'artificial' (non-abortive) means are not."[62] Sam and Bethany Torode, former advocates of NFP-only, have redacted their position to include barrier methods and explain their current theology this way:

We also see honest congruity with the language of the body by saying "no" to conception with our bodies (via barrier methods or sensual massage) when our minds and hearts are also saying "no" to conception. We don’t believe this angers God, nor that it leads to the slippery slope of relativism or divorce. We strongly disagree with the idea that this is a mortal sin.... it’s a theological attack on women to always require that abstinence during the time of the wife’s peak sexual desire (ovulation) for the entire duration of her fertile life, except for the handful of times when she conceives.[32]

Catholics such as Charles Curran have also criticized the stance of Vitae on artificial birth control.[63]

^"In deciding whether or not to have a child, [spouses] must not be motivated by selfishness or carelessness, but by a prudent, conscious generosity that weighs the possibilities and circumstances, and especially gives priority to the welfare of the unborn child. Therefore, when there is a reason not to procreate, this choice is permissible and may even be necessary. However, there remains the duty of carrying it out with criteria and methods that respect the total truth of the marital act in its unitive and procreative dimension, as wisely regulated by nature itself in its biological rhythms. One can comply with them and use them to advantage, but they cannot be 'violated' by artificial interference." Source: Pope John Paul II, Castel Gandolfo, 1994